When to start vegetable and flower seeds indoors

How to get a jump on the growing season by starting vegetable and flower seeds indoors.

Many gardeners like to start vegetable and flower
seeds indoors during the winter months. It gives us a chance to shake off the winter blahs, keeps us focused on our favorite hobby and we get to eat tomatoes and peppers before our bought-seedlings-at-the-nursery-center neighbors do.

To the novice, seed starting can be intimidating, but it’s really quite easy. You don’t need much in the way of special equipment, but if you wish, you can utilize grow lights and heat mats for best results.

Many beginning gardeners use seed starting systems like the Burpee Seed Starting Kit which has 1.5″ square cells in which you place the seeds and starter pellets (a compressed starter medium which expands when watered). It’s a great system, but I found that I’m all thumbs when it comes to transferring the tiny seedlings from the small cells into larger pots. Now I use 3″ square or round pots and let the seedlings grow in them undisturbed until they’re ready for transplanting into my garden.

Seed starting steps

The first step is to fill each starter pot with seed starting mix to within 1/2″ of the top and water until moist. Sow seeds, 3 spaced evenly around the center, and cover with an additional (roughly) 1/4″ seed starting mix. With your fingers, gently push down on the surface to remove any air pockets – the seeds need to come in contact with the starter mix in order to germinate. You’ll start most seeds this way – some you’ll plant a little deeper, some you’ll let lay on the surface – refer to the planting directions that come with your seeds.

Even though you’ll ultimately only keep one seedling in each starter pot, it’s best to use multiple seeds as a hedge against the chance that some of the seeds won’t germinate. That way you’re not left with any empty starter pots.

Once all of the starter pots are filled, topped off and watered (not too much, just moist), place the pots in a shallow plastic tray to catch any overflow or spills and place near a sunny window (for just a few seedlings) or on a table where you’ll be using grow lights overhead (much preferred to a windowsill). Use a heat mat to encourage seeds to germinate faster, because faster germination results in a healthier plant.

Cover the starter pots with a sheet of translucent plastic or plastic dome to seal in moisture – it’s important that the top of the potting medium never dries out – the idea is to create a mini greenhouse. It’s easy to tell if it’s working – you’ll see condensation on the inside of the plastic.

Seeds like a cozy room temperature

If you don’t use heat mats, make sure you keep the room air temperature around 70 degrees. Heat mats without thermometers do a good job of warming the starter medium sufficiently, but those with thermometers are even better, allowing specific control.

Lift the plastic sheet or dome each day to make sure that the top surface of the seed starter mix is still moist. When necessary, use a spray bottle to mist the top of each peat pot, getting the starter medium moist, not soaked.

Seedlings in peat pot trays. Popsicle sticks note which cultivar is planted in each

The time it takes for your seeds to germinate depends on what you’re growing, but as a rule of thumb, between 3-10 days. Once the seedlings are up, remove the plastic dome or sheeting. If you leave it on after this point you may invite a serious fungal disease called damping off.

When you take off the plastic sheeting, you’ll be exposing the surface of each pot to more airflow, so they’re now more likely to dry out faster. From here on, the seedlings will have to be misted perhaps twice each day, depending on the humidity in the room. It’s sufficient to just mist the top of each cell’s potting medium, as the seedling’s tiny roots are just underneath the surface at this point. Add a small amount of granulated organic fertilizer just once – that’s all the nutrients the seedlings will need before moving into your garden.

When the seedlings are about two inches tall (when they have their second set of leaves), look for the healthiest seedling in each cell. That would be the one that’s growing sturdiest, greenest, leafiest, etc. Snip the other seedlings in that cell with a small scissors. Do not pull out the seedlings you wish to discard, as this may damage the “keeper” seedling’s roots. The snipped seedlings will die in a few days.

Hardening off

When the seedlings are ready to be transplanted to your garden (anywhere from 4-12 weeks, depending on the plant), they’ll need to be hardened off for a week or more. Take your tray of seedlings outside every morning and place them in an area protected from direct sunlight, rain, and wind. The first morning, leave them outside for only an hour or two, then every day give them a little more time outside. Each night, take them inside to protect them from cold temperatures. This gets the seedlings used to temperature and light fluctuations so they can withstand the outdoor weather. If you transplant your seedlings directly from stable indoor conditions to the fluctuations of the real outdoors, the seedlings may suffer stress shock and die.

Transplanting your seedlings

When you transplant your seedlings into the garden, dig a hole at least twice as wide as the starter pot. If using a biodegradable starter pot like a peat pot, gently tear down its sides and place it in the hole. Biodegradable pots are meant to break down in garden soil quickly, but occasionally they fail to do so and a plant’s roots can’t make their way through it. I’ve learned to tear down the sides to help this process along. Fill the hole with a mix of compost and garden soil, press down into place with your hands to remove air pockets, and mulch a few inches around each transplant. Water it in well.

About Todd Heft

Todd Heft is an organic gardener and freelance garden writer who lives in the Lehigh Valley, PA and has gardened for most of his life. When he isn't writing or reading about organic gardening, he's gardening. His first book, "Homegrown Tomatoes: The Step-By-Step Guide to Growing Delicious Organic Tomatoes In Your Garden" is available on Amazon now. Google